Vikrant Sahu

Ultrahigh Performance Supercapacitor from Lacey Reduced Graphene Oxide Nanoribbons

High performance lacey reduced graphene oxide nanoribbons (LRGONR) were chemically synthesized. Holes created during the LRGONR synthesis not only enhanced the electrolytic accessibility but destacked all the graphene layers through protrusion at edge planes and corrugation in individual graphene. LRGONR in a supercapacitor cell showed ultrahigh performance in terms of specific capacitance and capacity retention. Consistently in aqueous, nonaqueous, and ionic electrolytes, LRGONR symmetric supercapacitor exhibited exceptionally high energy/power density, typically 15.06 W h kg(-1)/807 W kg(-1) in aqueous at 1.7 A g(-1), 90 W h kg(-1)/2046.8 W kg(-1) in nonaqueous at 1.8 A g(-1), and 181.5 W h kg(-1)/2316.8 W kg(-1) in ionic electrolyte at ∼1.6 A g(-1).

Synthesis of hydrophilic carbon black; role of hydrophilicity in maintaining the hydration level and protonic conduction

We report the low-temperature (250 °C) synthesis of high-performance hydrophilic carbon black for application as a conducting filler in supercapacitor electrodes. Increased water content, due to the hydrophilicity, maintained the uniform hydration level of MnO2/carbon composite electrodes, with good protonic conduction. This results in an increase in the total specific capacitance by 24%.

Nitrogen-doped carbon nanosheets for high-performance liquid as well as solid state supercapacitor cells

In this article N-doped carbon nanosheets (NCNS), formed by carbonizing polyaniline nanosheets (PNS), are reported. PNS were pyrolyzed at different temperatures (400–600 °C) to get different doping levels of nitrogen in the carbon sheets. The PNS carbonized at 400 °C (NCNS 400) exhibited high electrochemical performance due to a high inter-planar distance of 0.45 nm and high percentage (15 wt%) of N-based functionalities. NCNS 400 shows consistently high charge storage capacity in solid (PVA/H2SO4) and aqueous (1 M H2SO4) electrolytes. The NCNS 400 supercapacitor cell showed high energy density in 1 M H2SO4 (21.6 W h kg−1 at a power density of 293.91 W kg−1) and PVA/H2SO4 (9.8 W h kg−1 at 288 W kg−1). Further, the low relaxation time constant (τo) with low iR-drop and high capacitance retention (99.3%: H2SO4 and 99.8; PVA/H2SO4) is attributed to the improved structural properties upon nitrogen doping in the carbon sheets.